Engineering Commons^™

Formulation And Characterization Of Poly(Β-Amino Ester) Networks For Controlled Delivery Of Antioxidants In Pharmaceutical Applications, Vinod Shivaji Patil

Theses and Dissertations--Chemical and Materials Engineering

Oxidative stress, which reflects an imbalance between oxidants and endogenous antioxidants, is known to be a cause as well as an effect of health conditions such as cancer, diabetes, Alzheimer’s disease, Parkinson’s disease and ischemia-reperfusion injury. Antioxidants have shown promising results in vitro in controlling oxidative stress. However, years of in vitro studies have failed to translate into effective clinical interventions for controlling oxidative stress in the disease conditions. This has been due to low bioavailability and lower stability of antioxidants. Poly(antioxidant β-amino esters) (PABAE) are a recently-developed class of biodegradable polymeric hydrogels that have shown promise in their ability …

Understanding Glycoside Hydrolase Processivity For Improved Biomass Conversion, Suvamay Jana

Theses and Dissertations--Chemical and Materials Engineering

In nature, organisms secrete synergistic enzyme cocktails to deconstruct crystalline polysaccharides, such as cellulose and chitin, to soluble sugars. The cocktails consist of multiple classes of processive and non-processive glycoside hydrolases (GH) that aid in substrate accessibility and reduce product inhibition. Processive GHs attach to chain ends and hydrolyze many glycosidic linkages in sequence to produce disaccharide units before dissociation, and as such, are responsible for the majority of hydrolytic bond cleavages. Accordingly, processive GHs are targets for activity improvements towards efficient and economical biomass conversion. However, the mechanism and factors responsible for processivity are still not understood completely at …

The Effect Of Pore Density And Distribution On Fatigue Weak Links In An A713 Cast Aluminum Alloy, Rami A. Almatani

Theses and Dissertations--Chemical and Materials Engineering

The effects of pore density and distribution were investigated on the fatigue crack initiation behavior in an A713 sand cast aluminum alloy plate of 12 mm thickness. The applied stress- the number of cycles to failure (S-N) curves of the samples taken from 2 mm and 5 mm from the free surface were obtained using four-point bend fatigue testing at room temperature, frequency of 20 Hz, stress ratio of 0.1, sinusoidal waveform, and in ambient air. The fatigue strengths of both, the 2 mm and 5 mm samples were 60% of the yield strength (σy=171.9 MPa) of the …

Utilization Of Bio-Renewable Lignin In Building High Capacity, Durable, And Low-Cost Silicon-Based Negative Electrodes For Lithium-Ion Batteries, Tao Chen

Theses and Dissertations--Chemical and Materials Engineering

Silicon-based electrodes are the most promising negative electrodes for the next generation high capacity lithium ion batteries (LIB) as silicon provides a theoretical capacity of 3579 mAh g^-1, more than 10 times higher than that of the state-of-the-art graphite negative electrodes. However, silicon-based electrodes suffer from poor cycle life due to large volume expansion and contraction during lithiation/delithiation. In order to improve the electrochemical performance a number of strategies have been employed, such as dispersion of silicon in active/inactive matrixes, devising of novel nanostructures, and various coatings for protection. Amongst these strategies, silicon-carbon coating based composites are one …

Synthesis And Energy Applications Of Mesoporous Titania Thin Films, Syed Z. Islam

Theses and Dissertations--Chemical and Materials Engineering

The optical and electronic properties of TiO₂ thin films provide tremendous opportunities in several applications including photocatalysis, photovoltaics and photoconductors for energy production. Despite many attractive features of TiO₂, critical challenges include the innate inability of TiO₂ to absorb visible light and the fast recombination of photoexcited charge carriers. In this study, mesoporous TiO₂ thin films are modified by doping using hydrogen and nitrogen, and sensitization using graphene quantum dot sensitization.

For all of these modifiers, well-ordered mesoporous titania films were synthesized by surfactant templated sol-gel process. Two methods: hydrazine and plasma treatments have been …

Functionalization Of Silver Nanoparticles On Membranes And Its Influence On Biofouling, Conor G. Sprick

Theses and Dissertations--Chemical and Materials Engineering

Ultrafiltration (UF) processes are often used as pretreatment before more retentive/costly processes, such as nanofiltration and reverse osmosis. This study shows the results of low-biofouling nanocomposite membranes, loaded with casein-coated silver nanoparticles (casein-Ag-NPs). Membranes were cast and imbedded with Ag-NPs using two approaches, physical blending of Ag-NPs in the dope solution (^PAg-NP/CA membranes) and chemical attachment of Ag-NPs to cast membranes (^CAg-NP/CA membranes), to determine their biofouling control properties. The functionalization of Ag-NPs onto the CA membranes was achieved via attachment with functionalized thiol groups with the use of glycidyl methacrylate (GMA) and cysteamine chemistries. The …

Understanding And Improving Manufacturing Processes For Making Lithium-Ion Battery Electrodes, Mohanad N. Al-Shroofy

Theses and Dissertations--Chemical and Materials Engineering

Lithium-ion batteries (LIBs) have been widely used as the most popular rechargeable energy storage and power sources in today’s portable electronics, electric vehicles, and plug-in hybrid electric vehicles. LIBs have gained much interest worldwide in the last three decades because of their high energy density, voltage, rate of charge and discharge, reliability, and design flexibility. I am exploring the possibility of developing battery manufacturing technologies that would lower the cost, reduce the environmental impact, and increase cell performance and durability.

This dissertation is focused firstly on understanding the effect of mixing sequence (the order of introducing materials) and optimizing the …

Pore-Confined Carriers And Biomolecules In Mesoporous Silica For Biomimetic Separation And Targeting, Shanshan Zhou

Theses and Dissertations--Chemical and Materials Engineering

Selectively permeable biological membranes composed of lipophilic barriers inspire the design of biomimetic carrier-mediated membranes for aqueous solute separation. This work imparts selective permeability to lipid-filled pores of silica thin film composite membranes using carrier molecules that reside in the lipophilic self-assemblies. The lipids confined inside the pores of silica are proven to be a more effective barrier than bilayers formed on the porous surface through vesicle fusion, which is critical for quantifying the function of an immobilized carrier. The ability of a lipophilic carrier embedded in the lipid bilayer to reversibly bind the target solute and transport it through …

Charge Transport In Electronic-Ionic Composites, Long Zhang

Theses and Dissertations--Chemical and Materials Engineering

The goal of this thesis is to generate fundamental understandings of charge transport behaviors of composites consisting of garnet structured Al substituted Li₇La₃Zr₂O₁₂ (LLZO) electrolyte and LiCoO₂ electrode. In order to take full advantage of all-solid-state batteries, bulk type composite electrodes should be introduced to increase energy and power density. However, the charge utilization of bulk type composite electrodes is quite low. Understanding ionic conduction behavior is, therefore, important for improving the performance of all-solid-state batteries, because ion conduction within solids depends on effective pathways. Electronic conductivity can be easily compensated by …

Acenes, Heteroacenes And Analogous Molecules For Organic Photovoltaic And Field Effect Transistor Applications, Devin B. Granger

Theses and Dissertations--Chemistry

Polycyclic aromatic hydrocarbons composed of benzenoid rings fused in a linear fashion comprise the class of compounds known as acenes. The structures containing three to six ring fusions are brightly colored and possess band gaps and charge transport efficiencies sufficient for semiconductor applications. These molecules have been investigated throughout the past several decades to assess their optoelectronic properties. The absorption, emission and charge transport properties of this series of molecules has been studied extensively to elucidate structure-property relationships. A wide variety of analogous molecules, incorporating heterocycles in place of benzenoid rings, demonstrate similar properties to the parent compounds and have …

Deconvolving The Steps To Control Morphology, Composition, And Structure, In The Synthesis Of High-Aspect-Ratio Metal Oxide Nanomaterials, Lei Yu

Theses and Dissertations--Chemistry

Metal oxides are of interest not only because of their huge abundance but also for their many applications such as for electrocatalysts, gas sensors, diodes, solar cells and lithium ion batteries (LIBs). Nano-sized metal oxides are especially desirable since they have larger surface-to-volume ratios advantageous for catalytic properties, and can display size and shape confinement properties such as magnetism. Thus, it is very important to explore the synthetic methods for these materials. It is essential, therefore, to understand the reaction mechanisms to create these materials, both on the nanoscale, and in real-time, to have design control of materials with desired …

Mech 350: Introduction To Dynamics And Controls Of Engineering Systems—A Peer Review Of Teaching Project Benchmark Portfolio, Benjamin S. Terry

UNL Faculty Course Portfolios

There are two purposes of this portfolio. The first purpose is to outline and explain my approach to teaching this classic and fundamental course. I highlight in detail the purpose and curricula, the desired outcomes, and the goals and objectives. I also describe how the course activities and my teaching methodology support the course objectives. The second purpose of this portfolio is to describe a simple course modification—the introduction of a recitation session—and to test in a preliminary way the effect of this change on students’ attitudes towards the examples worked out in class. The results show that in the …

Meng 3250: Mechanics Of Elastic Bodies—A Peer Review Of Teaching Project Benchmark Portfolio, Jinying Zhu

UNL Faculty Course Portfolios

This portfolio focuses on mechanics of materials (course title: Mechanics of Elastic Bodies), a sophomore level course taken primarily by civil engineering and architectural engineering majors on Omaha campus. It is a prerequisite for broad range of courses in mechanical, civil and agricultural engineering majors. This course studies the mechanics of solids with applications to science and engineering, including stress, strains and deformation in structural elements (axial, torsional and bending), shear and moment diagram for beams, and a brief introduction to material failure mechanisms.

This portfolio describes the teaching methods used to help students understand the fundamental knowledge about material …

Cive 463: Traffic Engineering—A Peer Review Of Teaching Project Benchmark Portfolio, John Sangster

UNL Faculty Course Portfolios

This course portfolio documents the backward design of a senior-level design elective course in traffic engineering within the Department of Civil Engineering at the University of Nebraska. An extensive discussion of stakeholder needs for the course is followed by an analysis of formative and summative feedback assessments that are designed to meet the needs of a heterogeneous group of students in the course. As a senior-level design elective, there is a wide variety of interest levels among participants in the course, varying from those who have experience with internships in the topic and offer letters to conduct work in this …

The Effects Of Fiber Orientation And Volume Fraction Of Fiber On Mechanical Properties Of Additively Manufactured Composite Material, Suresh Chandra Kuchipudi

All Graduate Theses, Dissertations, and Other Capstone Projects

Additive manufacturing (AM) also known as 3D printing has tremendous advancements in recent days with a vast number of applications in industrial, automotive, architecture, consumer projects, fashion, toys, food, art, etc. Composite materials are widely used in structures with weight as a critical factor especially in aerospace industry. Recently, additive manufacturing technology, a rapidly growing innovative technology, has gained lot of importance in making composite materials. The properties of composite materials depend upon the properties of constituent’s matrix and fiber. There is lot of research on effect of fiber orientation on mechanical properties of composite materials made using conventional manufacturing …

Why Mobile Money Users Keep Increasing? Investigating The Continuance Usage Of Mobile Money Services In Tanzania, Daniel Koloseni, Herman Mandari

Journal of International Technology and Information Management

This study examined factors that affect continuance usage of mobile money services in Tanzania. The Theory of Planned Behavior was adopted as a theoretical foundation of the study. The theory was further extended by including the constructs of perceived cost, perceived trust and satisfaction as determinants of mobile money service continuance usage behaviour. A total of 309 valid and reliable responses collected using questionnaires were used for data analysis. The data were analysed using Structural Equation Modeling (SEM) approach. The findings depict that perceived trust, attitude and perceived behavioral control have significant influence on continuance behavioral intention while perceived trust, …

A Survey On Research Gaps In Chronic Traumatic Encephalopathy And American Football Players, Thomas Brent Ferguson

Honors Theses

Chronic Traumatic Encephalopathy (CTE) has recently received extensive media coverage, significantly increasing interest in concussions and their relation to the brain disease. As research continues on the disease and the protein Tau that is associated with it, it is imperative to find a correlation between any possible causation other than concussions. All American football players suffer subconcussive impacts, yet only some are diagnosed with the disease, leading most to believe there is something missing. Interviews were conducted with multiple university officials who work in sports and health, former football players, and team doctors. After interviews, 18 former football players who …

Skintronics: Wireless, Skin-Wearable Electronics For Monitoring Of Electrocardiogram, Matthew B. Piper, Woon-Hong Yeo, Yongkuk Lee

UROP Posters

The ECGs I micro-fabricate are designed to be flexible, stretchable and wireless circuits that can be applied to the skin directly. The device is encased in a conformal, silicon-like substrate, that allows the ECG to be attached with the electrodes. Each electrode has been previously measured and verified that it will be correctly placed for an accurate reading. Prototyping this ECG/electrode device allows the user to mount the prototype directly to the patient without having to attach and wire ten other electrodes. This prototype solves the issue that comes about when a doctor, nurse or emergency medical technician must attach …

The Bamboo Ceiling: A Study Of Barriers To Asian American Advancement, Emily Cheng

UROP Posters

The idea of cultural diversity in the workplace is a popular one, generating much discussion about the inclusion of and affirmative action toward minorities. However, these conversations rarely involve Asian Americans, who despite above-average levels of educational achievement, household income, and employment, find themselves underrepresented in and shut-out of upper-level management positions. In this project, I investigated the stereotype of East-Asian Americans as a model minority (created by non-Asians) to find out why East-Asian Americans are underrepresented in upper-level management in corporate workplaces, a phenomenon known as the “bamboo ceiling.” I explored a variety of scholarly sources that analyzed the …

Biochemical Variation In Caribbean Sponges Of The Genus Aplysina, Sarah L. Criddle

Honors Theses

Sponges are among the simplest multicellular organisms, consisting of groupings of cells with similar functions rather than true tissues. Nonetheless, sponges are ecologically significant in many marine environments, including coral reefs. They are sedentary organisms that feed by filtration from the water column, which contributes to the numerous roles they play on coral reefs, including upkeep of the reef, production of usable energy, and recycling of nutrients. Like all multicellular organisms, sponges are made up of biologically significant macromolecules. These macromolecules provide the energy for the sponge, and their relative concentrations determine how sponges can store and access the energy …

Detection And Interpretation Of Fluorescence Signals Generated By Excitable Cells And Tissues, Anthony J. Costantino

Graduate Dissertations and Theses

Part 1: High-Sensitivity Amplifiers for Detecting Fluorescence
Monitoring electrical activity and Cai 2+ transients in biological tissues and individual cells increasingly utilizes optical sensors based on voltage-dependent and Cai 2+-dependent fluorescent dyes. However, achieving satisfactory signal-to-noise ratios (SNR) often requires increased illumination intensities and/or dye concentrations, which results in photo-toxicity, photo-bleaching and other adverse effects limiting the utility of optical recordings. The most challenging are the recordings from individual cardiac myocytes and neurons. Here we demonstrate that by optimizing a conventional transimpedance topology one can achieve a 10-20 fold increase of sensitivity with photodiode-based recording systems (dependent on …

Robust Vehicle Routing In Disaster Relief And Ride-Sharing: Models And Algorithms, Yinglei Li

Graduate Dissertations and Theses

In this dissertation, the variants of vehicle routing problems (VRPs) are specifically considered in two applications: disaster relief routing and ride-sharing. In disaster relief operations, VRPs are important, especially in the immediate response phase, as vehicles are an essential part of the supply chain for delivering critical supplies. This dissertation addresses the capacitated vehicle routing problem (CVRP) and the split delivery vehicle routing problem (SDVRP) with uncertain travel times and demands when planning vehicle routes for delivering critical supplies to the affected population in need after a disaster. A robust optimization approach is used for the CVRP and the SDVRP …

Design Of Experiment Analysis Of An Electronics Package Lid Using Finite Element Analysis, Nupur Bajad

Graduate Dissertations and Theses

A design of experiment analysis is reported on data from warpage simulations using finite element analysis of a lidded electronics package. Warpage in a lid of an optical electronics package can detrimentally affect the reliability of the package as well as its optical performance. The present study focuses on the variety of materials and designs of lids relevant to recent technologies in electronics packaging. The finite element analysis (FEA) formulation in this study accurately predicts deformation and warpage in the elastic region with optimal computational time achieved through a choice of boundary conditions and mesh sensitivity studies.

The results from …

Understanding The Intrinsic Electrochemistry Of Ni-Rich Layered Cathodes, Shawn W. Sallis

Graduate Dissertations and Theses

The demand for energy is continually increasing overtime and the key to meeting future demand in a sustainable way is with energy storage. Li-ion batteries employing layered transition metal oxide cathodes are one of the most technologically important energy storage technologies. However, current Li-ion batteries are unable to access their full theoretical capacity and suffer from performance limiting degradation over time partially originating from the cathode and partially from the interface with the electrolyte. Understanding the fundamental limitations of layered transition metal oxide cathodes requires a complete understanding of the surface and bulk of the materials in their most delithiated …

The Evaluation Of Az66, A Highly Selective Sigma-1 And Sigma-2 Receptor Antagonist, For Its Anti-Convulsive Effects In C57bl/6 Mice, Jamie Stone

Honors Theses

The Evaluation of AZ66, A Highly Selective Sigma-1 and Sigma-2 Antagonist, for Anticonvulsive Effects in C57Bl/6 Mice (Under the direction of Lisa Wilson and Dr. Christopher McCurdy) Sigma receptors have become a popular subject for research the past few decades, but there is still much mystery behind these receptors and how they work. Researchers have found that sigma receptor antagonists can attenuate cocaine induced convulsions, however, limited research has been conducted on the effects of these antagonists on convulsions that mimic the types of seizures associated with epilepsy. Therefore, the aim of the current study was to evaluate AZ66 (20 …

The Effect Of Golf Shoe Characteristics On Static Balance Over An Extended Duration, Jordan Colbert

Honors Theses

Golf performance is greatly impacted by balance ability, specifically during a golfer's swinging and putting motion. Previous studies have found that certain shoe characteristics can affect balance; however, no such study has been conducted for golf shoes. This study's objective was to compare balance scores between three different golf shoe styles and determine which style or characteristics serve golfers best in improving balance under quiet standing conditions over time. Twelve adults (age: 23.4 ± 2.2 years; height: 181.5 ± 9.0 cm; mass: 95.8 ± 18.6 kg) participated in this study. Each participant made four visits, one for each footwear condition: …

The Effects Of Ultrasonic And Photochemical Pretreatment On Heating Value And Carbon Capturing Ability Of Fast Pyrolysis-Derived Biochars, Jordan Houry, Dong Joon Kim, Cary Roy

Honors Theses

Slow pyrolysis biochar has been shown to be receptive to ultrasonic and photochemical pretreatment that raises the heating value, surface area, and carbon content of the samples. This experiment was designed to test the feasibility of substituting fast pyrolysis derived biochar in place of slow pyrolysis biochars in order to reduce production times. Furthermore, new biomasses (switchgrass, rice husk, and rice straw) were tested for their receptiveness to pretreatment methods. It was ultimately determined that fast pyrolysis biochars that were exposed to pretreatment increased their carbon content and surface area but did not experience a heating value increase to the …

Hot-Fire Testing Of An Af-M315e 1-Newton Thruster, Alex Mcgee

Honors Theses

AF-M315E is a green monopropellant currently being investigated for use as a potential replacement for hydrazine in low-thrust spacecraft propulsion applications. To support devel- opment e↵orts, a series of hot-fire tests were conducted to assess the performance of AF-M315E in a 1N thruster. Preliminary design and analysis shows an increase in performance versus a comparable hydrazine system. Testing was conducted with a 1N TZM (titanium, zinc, and molybdenum alloy) thruster in late July 2016 in collaboration with the Spacecraft Propulsion Systems o ce (ER23) at Marshall Space Flight Center (MSFC). Testing focused on character- izing the transient behavior of the …

The Effect On Postural Balance As A Result Of Different Types Of Golf-Specific Footwear Over An Extended Duration, Alice Mcgee

Honors Theses

The sport of golf is increasingly popular within the United States, with an estimated 35 million participants worldwide. To be successful, the golf swing, regarded as a difficult biomechanical motion to accomplish, needs to be accurate and powerful. A proper swing incorporates a weight shift from the rear foot to the leading foot, which indicates that balance is crucial to maintain. The purpose of this study was to examine the effect of golf-specific footwear on static balance over an extended duration in order to relate it to golf performance. Twelve recreationally trained males (age: 23.4±2.2 years; height: 181.5±9.0cm; mass 95.8±18.6 …

Dynamic Testing Of Bovine Cortical Bone, Kenton Wong

Honors Theses

Bone is the primary structural element of mammalian animals. It plays a critical role in support, strength, and resilience, and has been the subject of many investigations into its material properties. The high strain rate behavior of bone has remained relatively unexplored, however, and its properties under dynamic loads perpendicular to the diaphysis of the bone are somewhat poorly understood. Bone is an anisotropic material and displays different properties depending on its orientation during testing. It is known that bone is weaker under a compressive load in the transverse direction, but the relationship has not been tested at high strain …